Great Salt Lake

The Great Salt Lake is a shallow body of saltwater located in Northwestern Utah, between the Wasatch Range on the east and the Great Salt Lake Desert on the west. It is the 33rd largest lake in the world and the largest salt lake in North America, covering an area around 1,700 square miles. The lake is one of Utah's largest tourist attractions.

Before the Great Salt Lake, there was Lake Bonneville. Lake Bonneville was a large lake covering about 20,000 square miles of western Utah and smaller portions of eastern Nevade and southern Idaho. It occupied the lowest, closed depression in the eastern Great Basin. Lake Bonneville was a large, ancient lake that existed from about 32 to 14 thousand years ago. It occupied the lowest, closed depression in the eastern Great Basin and at its largest extent covered about 20,000 square miles of western Utah and smaller portions of eastern Nevada and southern Idaho. At its largest, Lake Bonneville was about 325 miles long, 135 miles wide, and had a maximum depth of over 1,000 feet. Approximately16,800 years ago, the lake rose and caused a catastrophic flood. Researchers believe that the flood probably lasted less than a year. After the Lake Bonneville flood, the Great Basin gradually became warmer and drier. Therefore, Lake Bonneville began to shrink due of increased evaporation. What remained of Lake Bonneville is now the Great Salt Lake and it occupies the lowest depression in the Great Basin.

The first discovery of the Great Salt Lake was by the Spanish missionary explorers Dominguez and Escalante, who first learned of the Great Salt Lake from the Native Americans in 1776; however, they never actually saw it. The first white person known to have visited the lake was Jim Bridger in 1825. It is said that Etienne Provost may have beaten Jim Bridger, but there is no proof of this. The first scientific examination of the lake was in 1843 by John C. Fremont and Kit Carson. Kit Carson even carved a cross into a rock near the summit of Fremont Island, which is one of the islands located in the Great Salt Lake, which can still be seen today.

The Great Salt Lake averages approximately 75 miles long by 35 miles wide and 33 feet deep. However, its size and depth vary both seasonally and over long term. The amount to which it changes depends primarily on the balance of the amount of water that enters the lake and the amount of water that exits. On average, the lake level changes only about one to two feet annually. The lake rises to its highest level usually during May through July, after the melting of the mountain snowpack, and drops to its lowest level usually during October through November after the hot summer months. From 1847 to today, the level of the lake has varied over a range of 20 feet, reaching its ultimate low of 4,191.35 feet in 1963 and its high of 4,211.85 feet in 1986-1987. The average level of the lake is about 4,200 feet. Since the Great Salt Lake is a extremely shallow, small changes in the water level can greatly affect the shoreline.

The lake contains eleven islands. Seven of these islands are in the southern portion of the lake and four are in the northwestern portion. The large islands in the southern portion are named Antelope, Stansbury, Fremont, and Carrington. The smaller islands are named Badger, Hat (Bird), and Egg. The four small islands in the northwestern portion are Dolphin, Gunnison, Cub, and Strongs Knob. Antelope Island is 36 square miles and has been inhabited since pioneer times. There is a small ranch house owned by the Utah Division of Parks and Recreation that is said to be the state's oldest Anglo-built structure on its original foundation and the longest continually inhabited building in Utah and is opened during the summer for tours. Fremont Island was inhabited by a Salt Lake County probate judge, Judge Werner, and his family from 1884 to 1891. Both Gunnison and Carrington Islands were inhabited for short periods of time, but did not fair as well and were unsuccessful in the end. Antelope Island has been owned by the State of Utah since 1980 and is home to buffalo, antelope, deer and many other animals.

With the name, the Great Salt Lake, it's obvious that it is mostly made up of salt. The lake is very similar to that of ocean water, but is actually even saltier. Besides salt, the lake is also made up of sodium and chloride, which are the major ions. Also found in the water is sulfate, magnesium, calcium, and potassium. All of the salt in the lake came from what was found in Lake Bonneville. Though Lake Bonneville was considered mostly fresh water, it still contained salt. This salt concentrated as the water evaporated, leaving mostly only salt behind. This is not the only reason the lake is so salty. About two million tons of dissolved salts enter into the lake each year through rivers entering the lake. The lake's salinity has ranged from a little less than 5 percent, which is just a little above that of sea water, to almost 27 percent. As the lake rises, its salinity drops. This is because the same amount of salt is being dissolved in more water; therefore, the lower the level of the lake, the saltier the lake will become.

The Great Salt Lake receives 66 percent of its water from four main rivers and many small streams, 31 percent from direct precipitation into the lake, and 3 percent from ground water. The total average annual inflow to the lake is about 2.9 million acre feet of water. The main rivers entering the lake are the Bear, Weber, and Jordan. The Bear River starts in the Uinta Mountains and flows into the northeast arm of the lake. The Weber River also starts in the Uinta Mountains, but flows into the eastern part of the lake. The Jordan River starts at a freshwater Utah lake and flows into the southeast corner of the lake. With all of this water flowing into the lake, there needs to be an equal amount of water exiting in order for the constant water level of the lake. However, the Great Salt Lake is called a terminal lake, because there are no rivers flowing from it. Therefore, the water is lost from the lake mostly through evaporation. Evaporation rates are highest during the hot summer months and lowest during the winter. An average of about 2.9 million acre feet of water evaporates from the lake annually. This amount equals the amount of water entering the lake, which helps make the level of the lake remain so constant.

In 1983, the level of Great Salt Lake began to rise due to above average annual precipitation. By 1986, the lake rose nearly 12 feet, reaching its historical high. This rise in the lake level caused serious flooding, resulting in millions of dollars in property damage, especially around the south arm of the lake. This flooding disrupted major highways, railroad traffic, roads, beaches, farms, boating facilities and state/federal